<template>
  <el-select ref="select" style="width: 100%" :value="valueTitle" size="small" :disabled="disabled" :clearable="clearable" @clear="clearHandle">
    <el-option :value="valueTitle" :label="valueTitle">
      <el-tree  id="tree-option"
                ref="selectTree"
                :accordion="accordion"
                :data="options"
                :props="props"
                :node-key="props.value"
                :default-expanded-keys="defaultExpandedKey"
                @node-click="handleNodeClick">
      </el-tree>
    </el-option>
  </el-select>
</template>

<script>
export default {
  name: 'ebs-tree-select',
  props:{
    /* 配置项 */
    props:{
      type: Object,
      default:()=>{
        return {
          value:'id',             // ID字段名
          label: 'title',         // 显示名称
          children: 'children'    // 子级字段名
        }
      }
    },
    /* 选项列表数据(树形结构的对象数组) */
    options:{
      type: Array,
      default: ()=>{ return [] }
    },
    /* 初始值 */
    value:{
      type: String,
      default: ()=>{ return null }
    },
    /* 可清空选项 */
    clearable:{
      type:Boolean,
      default:()=>{ return true }
    },
    /* 自动收起 */
    accordion:{
      type:Boolean,
      default:()=>{ return false }
    },
    disabled: {
      type:Boolean,
      default:()=>{ return false }
    }
  },
  data() {
    return {
      valueId:this.value,    // 初始值
      valueTitle:'',
      defaultExpandedKey:[]
    }
  },
  mounted(){
    this.initHandle()
  },
  methods: {
    // 初始化值
    initHandle(){
      // alert('this.valueId=' + this.valueId)
      let that = this
      console.log(this.value)
      // 这里要延迟执行，否则有BUG
      setTimeout(function() {
        if(that.valueId){
          console.log(that.$refs.selectTree.getNode(that.valueId))
          that.valueTitle = that.$refs.selectTree.getNode(that.valueId).data[that.props.label]     // 初始化显示
          that.$refs.selectTree.setCurrentKey(that.valueId)       // 设置默认选中
          that.defaultExpandedKey = [that.valueId]      // 设置默认展开
        } else {
          that.valueTitle = null // 初始化显示
          that.$refs.selectTree.setCurrentKey(null) // 设置默认选中
        }
      },200)
      this.$nextTick(()=>{
        let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
        let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
        scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
        scrollBar.forEach(ele => ele.style.width = 0)
      })

    },
    // 切换选项
    handleNodeClick(node){
      this.valueTitle = node[this.props.label]
      this.valueId = node[this.props.value]
      //this.$emit('getValue',this.valueId)
      this.$emit('input',this.valueId)
      this.defaultExpandedKey = []
      this.$refs.select.visible = false
    },
    // 清除选中
    clearHandle(){
      this.valueTitle = ''
      this.valueId = null
      this.defaultExpandedKey = []
      this.clearSelected()
      //this.$emit('getValue',null)
      this.$emit('input',null)
    },
    /* 清空选中样式 */
    clearSelected(){
      let allNode = document.querySelectorAll('#tree-option .el-tree-node')
      allNode.forEach((element)=>element.classList.remove('is-current'))
    }
  },
  watch: {
    value(){
      this.valueId = this.value
      this.initHandle()
    }
  }
}
</script>


<style scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item{
  height: auto;
  max-height: 274px;
  padding: 0;
  overflow: hidden;
  overflow-y: auto;
}
.el-select-dropdown__item.selected{
  font-weight: normal;
}
ul li >>>.el-tree .el-tree-node__content{
  height:auto;
  padding: 0 20px;
}
.el-tree-node__label{
  font-weight: normal;
}
.el-tree >>>.is-current .el-tree-node__label{
  color: #409EFF;
  font-weight: 700;
}
.el-tree >>>.is-current .el-tree-node__children .el-tree-node__label{
  color:#606266;
  font-weight: normal;
}
</style>

